In "Brothers", Data takes over the ship, at the direction of Soong's signal. What always confused me about this was what the signal did to Data.

On the one hand, it seems unlikely that Soong was directly remote controlling Data, since stealing the Enterprise is a rather... criminal act. Aside from the obvious problems, it seriously endangers Data's career in Starfleet. While Soong does not like this career very much, I find it hard to believe he would intentionally sabotage it given their relationship. And Data appears to use a lot of knowledge of the Enterprise that Soong would not have (e.g. that you can turn off life support, lock out the computer, etc. as well as how to do all of those things)

Data himself does not remember what happened, so obviously he was not controlling his own actions, which we already knew because Data would not voluntarily steal the Enterprise.

What I'm left with is that Data was under the control of some kind of program that was simultaneously smart enough to steal the Enterprise, and dumb enough to steal the Enterprise. It probably had a directive like "Get Data to Terlina III by any means necessary and make sure nobody follows him down." What I don't understand is how Soong could possibly think this was a good idea. This program demonstrates a profound and breathtaking lack of ethical judgment, which is particularly confusing since we know Soong specifically programmed Data to be ethical and knows how to do it correctly. Soong knew (or should have known) that Data could have been in any number of situations in which other peoples' lives were at risk. There was obvious potential for a seriously bad outcome (which nearly happened) and Soong had the ability to prevent it. Why didn't he?

2 Answers
2

There wasn't much time

Soong reveals in 'Brothers' that he was dying - evidently he didn't have long to live. (Well, he actually dies in that episode, but I think we'd all agree that Lore's assault didn't help matters!)

In any event, because Soong was the only one with sophisticated knowledge of Data (that Soong knew of - he probably didn't know whether Juliana was still alive) and knew he was going to die soon, he likely used the homing signal once he had finished the emotion chip to get Data to him as fast a possible. There wouldn't be any point waiting until Data was off the ship or the Enterprise was not on a critical mission because

How would Soong know when this was the case in the first place - as far as Soong knew the Enterprise wasn't on a critical mission; it's not as though Starfleet would be broadcasting every movement of one of its starships, let alone the flagship

Soong was going to die soon and he says he dedicated his final years to rectify this problem for Data; the last thing he'd want is to have Data arrive and he had died with nobody to install the chip safely for him.

True he was dying but the clincher is that he wanted to preserve his seclusion from the world and not reveal himself to Starfleet.

After he and Juliana escaped from the crystalline entity's destruction of Omicron Theta, they lived in secret on a remote uninhabited planet Terlina III. Everyone presumed they were dead--and apparently they were ok with that. He was disgraced by his failure to produce a working positronic brain, and even after he successfully created one he still did not reveal himself or publish his findings or land a sweet gig at the Daystrom Institute. After Juliana-bot left him, he continued to live as a hermit.

So while it's true Soong knew he was dying, he could have contacted Starfleet and said he'd like to install an emotion chip and would you please send him over poste haste, but screw that. Sometimes subspace messages take days to go back and forth, and Soong has been living alone for decades and does not want to deal with people. Better to just press a button and Data comes running.

Soong knew that Data's ethical subroutines would generally protect passers-by from harm (though it is super odd that Data was apparently willing to risk/sacrifice the young boy Willie Potts by preventing him from getting medical attention).